1. Field of the Invention
The present invention relates to automatic devices that generate an alarm signal when a person attempts to steal clothing from a clothing retailer""s changing room by wearing said clothing.
2. Background
The general technology for video recognition of objects and other features that are present in a video data stream is a well-developed and rapidly changing field. One subset of the general problem of programming computers to recognize things in a video signal is the recognition of objects in images captured with a video image. So called blob-recognition, a reference to the first phase of image processing in which closed color fields are identified as potential objects, can provide valuable information, even when the software is not sophisticated enough to classify objects and events with particularity. For example, changes in a visual field can indicate movement with reliability, even though the computer does not determine what is actually moving. Distinct colors painted on objects can allow a computer system to monitor an object painted with those colors without the computer determining what the object is.
Remote security monitoring systems in which a video camera is trained on a subject or area of concern and observed by a trained observer are known in the art. Machine identification of faces is a technology that is also well-developed. In GB 2343945A directed to a system for photographing or recognizing a face, a controller identifies moving faces in a scene and tracks them to permit image-capture sufficient to identify the face or distinctive features thereof. For example, the system could sound an alarm upon recognizing a pulled-down cap or face mask in a jewelry store security system.
A monitored person""s physical and emotional state may be determined by a computer for medical diagnostic purposes. For example, U.S. Pat. No. 5,617,855, hereby incorporated by reference as if fully set forth herein, describes a system that classifies characteristics of the face and voice along with electroencephalogram and other diagnostic data to help make diagnoses. The device is aimed at the fields of psychiatry and neurology. This and other such devices, however, are not designed for monitoring persons in their normal environments.
The screening of individuals entering and leaving a clothing retailer""s fitting room has been accomplished in various ways. For example, WO 99/59115 describes a system that weighs goods taken into a fitting room and taken out upon leaving. If there is a discrepancy, the system notifies a security person. In EP 921505A2, a picture is taken of any individuals attempting to remove articles with electronic security tags attached to them. The tags are deactivated when the article is purchased. A similar system using radio frequency identification tags is described in WO 98/11520.
There remains in the art a need for a system that permits fitting rooms to be monitored automatically, but unobtrusively. Weighing goods requires that customers be subjected to the inconvenience of placing their articles on a scale. If the articles are incomplete or the system is not monitored, the system could be defeated. Security tags only work when a person leaves a particular area and must be removed, requiring that the retailer inconvenience customers and provide detectors near the exits of the fitting rooms.
Briefly, a fitting room monitoring system captures images of persons entering and leaving a fitting room or other secure area and compares the images of the same person entering and leaving. To insure that the images are of the same person, face-recognition is used. When the clothing worn or carried by the person entering is different from that worn by the same person as he/she leaves, an alarm is generated notifying a security person.
In an embodiment, the security system transmits the before and after images to permit a human observer to make the comparison. As an alternative to face recognition, the system may use other signature features available in a video signal of a person walking. For example, the height, body size, gait, and other features of the person may be classified and compared for the entering and leaving video signals to insure they are of the same person.
The system may be set up in an area where the customer must walk to enter and leave the fitting room or other venue. Since the conditions are controllable, highly consistent images and video sequences may be obtained. That is, lighting of the subject, camera angle relative to the subject, etc., can be made very consistent.
The system generates a signal that indicates the reliability of its determination that the images indicate the customer is leaving wearing something different from what he/she entered wearing. The reliability may be discounted based on various dress-independent factors, including the duration between the images based on an expected period of time the user remains in the fitting room, correlation of gait, body type, size, height, hair color, hair style, etc. When a reliability of a determination is above a specified threshold, the system generates a signal notifying a security person.
To further insure against the comparison of images of different people (and the resultant false-positives), the fitting rooms may be outfitted with sensors to indicate when they are occupied. The images or video sequences (or classification outputs resulting therefrom) may then be time-tagged. This could be accomplished by any means suitable for determining which room a customer enters. This includes additional cameras. Also, inputs of other modalities may be used in conjunction with video to identify individuals and thereby increase reliability. For example, the sound (e.g., spectral characteristics of sound of footfalls and frequency of gait) of the customer""s shoes as the customer walks may be sampled and classified (or the incoming and outgoing raw signals) and compared.
The detection and comparison of clothing may represent a relatively trivial image processing problem because many clothing articles produce distinct video image blobs. It is understood that clothing cannot always be characterized by a homogenous field of color or pattern. For example, a shiny leather or plastic jacket would be broken up. Thus, algorithms for detecting what clothing is preferably do not rely solely on closed fields of color in the video image. Preferably, the outline of the body may be used as a reference guide to permit an image to be segmented and the type of clothing article worn identified in addition to its color characteristics.
The invention will be described in connection with certain preferred embodiments, with reference to the following illustrative figures so that it may be more fully understood. With reference to the figures, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present invention only, and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the invention may be embodied in practice.